Landscape age and soil fertility, climatic stability, and fire regime predictability: beyond the OCBIL framework

Abstract

Hopper (Plant Soil 322:49-86, 2009) introduced landscape age, climate buffering, and soil nutrient status as descriptors for a continuum between old, climatically buffered landscapes characterised by low soil fertility (OCBIL) and young, often disturbed landscapes characterised by fertile soils (YODFEL). Hopper (Plant Soil 322:49-86, 2009) provided an important framework for biodiversity and conservation. We argue that Hopper's (Plant Soil 322:49-86, 2009) conceptual framework includes five areas worthy of further consideration. These include: (1) The appropriateness of the original three dimensions;(2) The need for deeper consideration of rejuvenation and disturbance within OCBILs. (3) Broadening the globally relevant range of environments. (4) Operationalising the definitions or dimensions. (5) Revisiting the scale and compatibility of the predictions. Here, we address the first four of these areas and offer an alternative conceptual framework based on the idea of Old Stable Landscapes (OSLs). We redefine Hopper's climate buffering as a dimension of climate stability, identify soil-impoverishment as a function of landscape age, and recognise fire regime predictability as a large-scale, long-term evolutionarily important dimension. In so doing, we construct a globallyrelevant, qualitative template to enable the testing of evolutionary-ecological hypotheses concerning biodiversity (e.g. species diversity, diversity gradients, endemism, speciation and extinction rates, cladogenesis, persistence of old lineages, refugial phenomena). Our template is characterised by having operationally defined dimensions, which can be used to design surveys and experiments to address the issues of biodiversity conservation, recovery, and restoration under variations in landscape age, climatic stability and fire regime.

Biodiversity hotspots and Ocbil theory

“…Vale of Clwyd has no endemic plants. Photos SD Hopper except inset by WR Barker framework, so it could be complicated to define what is old/new, what is buffered or not, and what are rich or poor soils (Mucina and Wardell-Johnson 2011). This problem is being addressed as various authors test components and predictions of Ocbil theory (e.g., Cowling et al 2015).…”

“…Critics have suggested that the Pantepui could not have experienced prolonged oceanic climatic buffering, due to its present location 300 km inland (Mucina and Wardell-Johnson 2011). However, sea-level fluctuations have altered this relationship materially at times, including the Cretaceous and Eocene highest oceanic stands (Miller et al 2005).…”

Limited pollen-mediated dispersal and partial self-incompatibility in the rare ironstone endemic Tetratheca paynterae subsp. paynterae increase the risks associated with habitat loss

“…paynterae ) are consistent with hypotheses that ancient stable landscapes favour mechanisms that have promoted local persistence rather than wide dispersal and colonizing ability (Hopper 2009). The ironstone ranges have ancient origins, with the majority formed in the Archean and lower Proterozoic eras, 3,800-542 mya (Lascalles 2007) and fit the definition of old stable landscapes as proposed by Hopper (2009), modified by Mucina and Wardell-Johnson (2011). Hopper (2009) argues that communities that have evolved on old stable landscapes may require different conservation strategies to those on more recently derived landscapes.…”

Canopy Profiling for Vegetation Mapping in South-Western Australian Forested Ecosystems

“…Accurately mapping the vegetation structure and biodiversity patterns in this global biodiversity hotspot is therefore vitally important for benchmarking and conservation planning in the face of anthropogenic climate change. However, vegetation mapping (type, condition, structure or floristic patterns) can be problematic in old and stable, but heterogeneous landscapes (Wardell-Johnson and Williams 1996;Mucina and Wardell-Johnson 2011), exemplified by much of south-western Australia. In this region, landscapes are muted and vegetation overstorey canopy relatively constant, despite a highly heterogeneous understorey associated with the geomorphology of these landscapes (Wardell-Johnson and Williams 1996).…”